From David Fisher,
Your Guide to Candle & Soap Making.
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Definition: "Less likely to cause an allergic reaction when used."

Hypo means "less than" not "none" - which means that "hypoallergenic" just means "less likely to cause an allergic reaction" than free from the possibility. It most likely means that the manufacturer has eliminated or reduced likely allergy causing ingredients like fragrances or preservatives. Similarly, the terms "allergy-tested", "dermatologist tested", or "non-irritating" have no industry standard, and hence, offer no guarantee of not causing allergic reactions.

Source: FDA - Cosmetic Safety: More Complex Than at First Blush